Perinephric hemorrhage in autosomal dominant polycystic kidney disease: CT and MR findings.

Perinephric hemorrhage is a rare complication of autosomal dominant polycystic kidney disease (ADPKD). Of 66 patients in our series, it occurred in two (3%) and their clinical and radiologic findings are described. Computed tomography accurately delineated both hematomas and revealed an underlying ruptured hemorrhagic renal cyst in one patient. Computed tomography did not show the cause of hemorrhage in the other patient, but magnetic resonance (MR) imaging detected an underlying hemorrhagic cyst. Perinephric hemorrhage in ADPKD probably results from rupture of hemorrhagic renal cysts into the perinephric space. Computed tomography is the optimal method for its evaluation. However, MR may supplement CT findings since it detects more hemorrhagic cysts than CT and helps distinguish them from carcinomas. Perinephric hemorrhage in ADPKD can usually be managed conservatively.